1. Field of the Invention
The present invention relates to a storage apparatus and an accessing method thereof; specifically, it relates to a storage apparatus whose storage blocks can be uniformly used and an accessing method thereof.
2. Descriptions of the Related Art
Due to rapid technological developments, many companies have manufactured various portable storage apparatuses using different materials and techniques. For example, these materials could be different forms of flash memories, such as NOR flash memories, NAND flash memories, NROM flash memories, and SLC/MLC flash memories.
Flash memories that are currently on the market typically use one or several blocks as the accessing unit. When data has been stored in the flash memory, the data are expected to be stored forever. However, flash memories currently on the market have some limitations on their circuit structures, which damage the accuracy of the stored data. That is, if the data is stored in the flash memory and has not been updated for a long time, the accuracy of the data will be damaged by the coupling effect of the reading and/or writing of other blocks.
In addition, current memory management and memory access methods have some drawbacks as well. Since all blocks are managed in the same way, the same physical blocks of the flash memory are accessed repeatedly if the user often uses only part of the flash memory. As a result, the frequently used blocks will not be able to be written on and can only be read from. As for the other blocks, although they are supposed to be able to be written on, they can only be read from. As a result, the usage of the flash memory is seriously decreased.
Therefore, due to the concerns raised from the aforementioned descriptions, it is important to find a way to maintain the accuracy of the stored data in the flash memory, as well as finding a way to uniformly use the blocks in the flash memory so that no blocks are left unused.